/Engine/Plugins/Experimental/GeometryScripting/Source/GeometryScriptingCore/Public/GeometryScript/GeometryScriptTypes.h
PolyGroupsFGeometryScriptGroupLayeridentifies a PolyGroup Layer of a Mesh. The Default Layer always exists, Extended layers may or may not exist.
[USTRUCT](Programming/UnrealArchitecture/Reference/Structs)([BlueprintType](Programming/UnrealArchitecture/Reference/Structs/Specifiers/BlueprintType)) struct FGeometryScriptGroupLayer
bool
bDefaultLayer
If true,the default/standard PolyGroup Layer is used
int
ExtendedLayerIndex
Indexof an extended PolyGroup Layer (which may or may not exist on any given Mesh)